1. Field of the Invention
The present invention generally relates to network switching. More specifically, the present invention provides techniques for effectively and efficiently switching cable lines to available active line cards.
2. Description of Related Art
A cable network headend such as a cable modem termination system typically includes multiple line cards connected to various cable lines. The cable lines may be coaxial cable lines or fibre optic lines connected to cable plants and cable networks. Since a variety of reasons can cause line card failure, mechanisms are often provided to support high availability and redundancy by providing redundant line cards.
In some examples, protect line cards are provided along with active line cards. For example, there may be one protect line card associated with five active line cards. If an active line card connected to a cable line fails, the cable line is switched over onto a protect line card. However, hardware mechanisms for switching the cable line over from a failed line card to a protect line card are limited. In many instances, the hardware switching mechanisms cause loss and inefficiency during both switchover and normal operation. Examples are the Weinschel external RF switch available from Weinschel Corporation of Frederick, Md. and the Motorola and Arris internal RF switches available from Motorola Corporation of Schaumburg, Ill. and Arris Corporation of Wayne, Pa., respectively. The available switches only support N+1 redundancy and require two separate cards for supporting upstream and downstream applications. Furthermore, the switches also require a 3 dB splitter or low isolation components which cause the DS signal quality to degrade.
Consequently, it is desirable to provide techniques for improving the mechanisms for providing redundancy in cable network headends.